A technology which has been studied by the present inventor is shown in FIGS. 1 and 2. A hair drier 101, devised for a portable use to utilize LPG, is comprised of a premixing chamber 105 disposed inside a cylindrical case 103 to allow LPG and air to be mixed, a combustion dish 107 composed of a porous combustion plate that blows out mixed gas obtained in the premixing camber 105, and an ignition plug 109 that ignites mixed gas ejected from the combustion dish 107 while including a primary combustion chamber 111 serving as a combustion cylinder to combust the above described mixed gas, a secondary combustion chamber 115 that performs nonflammable combustion through a combustion catalyst 113 in a forward area of the primary combustion chamber 111, and a heat exchanger 117 composed of a star shaped peripheral wall formed between peripheries of the above described primary combustion chamber 111 and the secondary combustion chamber 115 and the cylindrical case 103.
Also, disposed in a rear side wall of the premixing chamber 105 is a plurality of air apertures 119 to introduce outside air, and use is made of ceramics such as porous cordierite series and porous alumina as raw materials to generally serve as a carrier body of the combustor catalyst 113.
Further, disposed in the rear end wall of the premixing chamber 105 is a blower 125 that is comprised of a direct electric motor 121 mounted on a rearward area of the above premixing chamber 105, and an axial flow fan 123 adapted to be rotationally driven by the direct electric motor 121 to allow air, required for combustion in the cylindrical case 103 and a large volume of hot blast to be delivered.
The LPG tank, for storing LPG, to be supplied to the above described premixing chamber 105, and the battery (mainly a primary battery), serving as the power supply of the ignition plug 109, are accommodated in a handle, which is not shown, connected to the above described cylindrical case 103.
By the way, with the combustion type hair drier 101 of the related art, since air required for combustion of LPG is drawn through the plurality of air apertures 119 partly from a volume of blast delivered by the blower 125 needed to generate a large volume of hot blast, the occurrence of drop in the voltage of the battery, to cause drop in the above described volume of blast, results in short of air in volume to be required for combustion of LPG. As a result, a probability occurs in which mixed gas with oxygen deficiency arriving at the outlet 127 (exhaust port) is brought into contact with air at the outlet 127 followed by a resultant flame to cause combustion.
Moreover, it was found out that, without using the combustion catalyst 113 of FIG. 1, if the primary combustion chamber 111 is improved to allow combustion to internally occur in the cylinder, the combustion flame advances along the cylinder to the outlet 127 (exhaust port) and, hence, it was hard to effectuate combustion to obtain a minimal volume of heat required for the hair drier 101 unless a remarkably long cylinder or a combustion cylinder with a large diameter are employed. In this respect, the minimal volume of heat refers to a value of, for instance, a heat output of 450 W/H under a combustion condition of LPG with a value of approximately 390 Kcal/H. Consequently, the combustion type hair drier 101 of the related art takes the size two times the normal electric type hair drier and, with such a dimension, there occurs an issue of a practicability as a portable unit.
Further, as a method for efficiently achieving combustion without occurrence of the flame, although development work has been undertaken to utilize the combustion catalyst 113 as shown in FIG. 1 set forth above, due to the presence of this case suffered from a resultant heat accumulated in the center of the combustion catalyst 113 while, also, exchange of heat with blast is performed only through the heat exchanger 117 around the combustion catalyst 113, no probability occurs in exchange of heat accumulated in the center of the combustion catalyst 113 at which the maximum temperature rise occurs and experimental tests have revealed a result with a remarkably poor efficiency.
Moreover, due the presence of the surface area of the outlet 127 resulting from the heat exchanger 117 in an actual practice to lie in a less surface area, a pressure loss in blast takes place, causing an issue of reduction in a volume of blast.
In addition, a serious issue arising in the systems in the former and the latter set forth above suffers from an inability of achieving rapid cooling at the combusted portion even after the supply of LPG has stopped when in non-use and, therefore, it is probable for a fairly high temperature remains for a long period of time. Especially, even after an elapse of twenty minutes, it is hard for a hand to touch the unit in which the combustion catalyst 113 is utilized.
Also, although another improvement has been proposed to automatically operate the blower 125 for the purpose of cooling a condition in which, even after the use of the hair drier 101 has been terminated, the high temperature remains, an issue arises in that the portable unit, needed for standby between the end of use of the hair drier 101 and the end of cooling, becomes inconvenient and incommodious in use.
Further, even with the portable type cordless unit, it is required for a working condition, needed to a minimal extent, of the hair drier 101 to have a heat value of 450 W/H, converted in electric power, with a combustion energy of approximately 390 Kcal/H. Also, because of the portable type hair drier 101, it is required to have a size and weight which do not exceed those of the commercially available electric type hair drier in the related art practice.